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FAQs

Are the 0.04 micron particles used by the N95-Companion™ Mask Fit Tester appropriate for respirator fit testing?

Research has shown that there is no lower limit to the particle size that can be used for quantitative fit testing. There may be an upper limit near 2 microns. For more details, please refer to Application Note ITI-055 Penetration of Ambient Aerosols Through Respirator Face Seal Leaks.

Are there any cleanroom applications for the PortaCount® Respirator Fit Tester?

The PortaCount® Respirator Fit Tester can be used as a particle "sniffer" to find particle sources or leaks in HEPA filters. It cannot be used to monitor clean room particle levels because it cannot measure concentrations low enough. 1.0 particle per cc is equivalent to over 28,000 particles per cubic foot. Many clean rooms maintain particle concentrations below 100 particles per cubic foot.

Can I fit test with a respirator using chemical vapor cartridges?

NO. Chemical cartridges do not stop ambient air particles. Even though your employees use chemical cartridges in the work place you will have to do your fit testing with Class 99 or Class 100 HEPA cartridges. Combination chemical/HEPA cartridges usually will work fine. However, some chemical/vapor cartridges may release particles of sorbent material which will be interpreted as leakage by the PortaCount® Respirator Fit Tester. Use plain HEPA cartridges to be safe.

Can I lengthen the sampling hoses on the PortaCount® Respirator Fit Tester?

No. Do not lengthen the hose more that a foot or so. The purge time that is programmed into the PortaCount® Respirator Fit Tester firmware is calculated based on the flow rate of the pump and the volume of the sample tube. An increase in tube length could cause the PortaCount Respirator Fit Tester not to purge sufficiently between mask and ambient samples. It is all right to increase the tube length by a few inches (for an adapter) or to shorten the tube. If you elect to lengthen the sampling tubes check to make sure the PortaCount Respirator Fit Tester purges completely. Also make sure both tubes are the same length.

Can I use or test the PortaCount® Respirator Fit Tester in a corn oil or DOP chamber?

Yes. As long as you turn the aerosol concentration down to below the upper limit of the PortaCount® Respirator Fit Tester you can use other aerosols. Be aware that this will cause the PortaCount fit tester to need cleaning much sooner than it would using ambient air. TSI does not recommend using anything other than ambient air particles.

Can I use the PortaCount® Respirator Fit Tester to find leaks in HEPA filters?

Yes, using the PortaCount® Respirator Fit Tester in count mode allows very precise leak detection. Ambient air particles will not penetrate a good HEPA filter to any significant degree.

Can I use the PortaCount® Respirator Fit Tester to measure HEPA filter efficiency?

The PortaCount® Respirator Fit Tester can be used to measure filter efficiency, but only if a generated aerosol is used such as .12 or .3 micron DOP. Ambient air cannot be used since efficiency is a function of particle size and you don't know the size. Ambient air can be used with the PortaCount fit tester to leak check HEPA filters.

Can the PortaCount® Respirator Fit Tester be used to fit test disposable (filtering facepiece) respirators?

Yes. In June 2008, TSI redesigned the N95-Companion™ technology and it is now built into the PortaCount® Pro+ Model 8038. This redesigned instrument allows you to quantitatively fit test disposable respirators, including the popular N95 class. The PortaCount® Respirator Fit Tester has always been able to fit test HEPA, N100, R100, P100, N99, R99, and P99 disposables by itself without using the N95-Companion™ technology. Click here for information on the Model 8025-N95 Sampling Probe Kit that lets you install sample probes into disposable respirators. Prior to the introduction of the N95-Companion technology, the PortaCount® Respirator Fit Tester could not be used effectively with Dust-Mist (DM) or Dust-Mist-Fume (DMF) disposable respirators.

Exhaled moisture droplets have little effect on the PortaCount® Respirator Fit Tester for two reasons. One is that there are not enough of them to make a difference and the other is that large droplets either evaporate or impact with the walls of the sample tube before they reach the PortaCount fit tester. If a body-generated droplet were to be counted by the PortaCount fit tester, the result would be a fit factor that is lower than it should be. There is no possibility of overstating the fit factor.

Do I have to remove the alcohol cartridge from my PortaCount® Plus Respirator Fit Tester before I ship or store it? What happens if I forget?

You should always remove the cartridge and replace it with the storage cap whenever you ship or store the PortaCount® Plus Respirator Fit Tester. If you do not, you risk flooding the instrument. The storage cap keeps dirt out of the PortaCount Plus fit tester. A little dirt in the wrong place can cripple the instrument. Discipline yourself to always use the storage cap.

Do you need a probed mask?

Probed respirators are still a common way to perform quantitative fit testing. However, TSI and many of the U.S. respirator manufacturers have developed fit test adapters that allow you to fit test using the employee's own respirator. Contact your respirator manufacturer or contact TSI for more information.

Does OSHA give employers a choice of using either qualitative (QLFT) or quantitative (QNFT) fit test methods?

Yes and no. QLFT fit test protocols that exist at this time are only suitable for determining a fit factor of 100. OSHA allows you to use either QLFT or QNFT for fit testing respirators that require a fit factor of 100 (i.e. half-masks). Full-face masks need a fit factor of at least 500 so QNFT is the only choice at this time. If a QLFT for a fit factor of 500 is ever developed and accepted by OSHA, it would be allowed for use with full-face respirators. Refer to Application Note ITI-032 Don't Use Qualitative Fit Testing for Full-Face Respirators for an explanation or read OSHA's explanation in the Respirator Protection Standard Preamble. Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 will help you locate this information.

Does the PortaCount® Respirator Fit Tester work with half-face and full-face respirators?

Yes. It will work equally well with either type of respirator. Keep in mind that the larger the internal volume of the respirator the longer the test subject should wear it before testing. This allows the ambient air particles that were trapped in the mask during donning to be purged out. Half masks take less than 30 seconds of breathing to purge. Full face masks may take over one minute.

Does the PortaCount® Respirator Fit Tester work with powered air purifying respirators (PAPR's)?

Yes. However, just as with SCBAs, fit testing must be done with the mask in negative-pressure mode using Class 100 (HEPA) filters. Fit testing a PAPR in negative-pressure mode is done in one of two ways. The most common way is to temporarily convert the mask to use HEPA filters instead of the usual air supply. Respirator manufacturers (and TSI) have special fit test adapters available specifically for this purpose. The other way is to share a permanently-probed, negative-pressure version of the same mask. Most respirator manufacturers offer negative-pressure versions of the same face piece used for their PAPRs. OSHA and ANSI endorse both methods. Testing may be done with the air supply on. However, this is performance testing, NOT fit testing. Many PAPRs have blower motors that generate particles. These particles are interpreted as leakage by the PortaCount® Respirator Fit Tester. If particles are present in the air supply, they must be removed with a HEPA filter before they reach the mask in order to run such a performance test.

Does the PortaCount® Respirator Fit Tester work with self contained breathing apparatus (SCBA) such as used by fire fighters?

Yes. However, just as with PAPRs, the respirator must be fit tested in negative-pressure mode using Class 100 (HEPA) filters. Fit testing an SCBA respirator in negative-pressure mode is done in one of two ways. The most common way is to temporarily convert the mask to use HEPA filters instead of the usual air supply. Respirator manufacturers (and TSI) have special fit test adapters available specifically for this purpose. The other way is to share a permanently-probed, negative-pressure version of the same mask. Most respirator manufacturers offer negative-pressure versions of the same face piece used for their SCBAs. OSHA and ANSI endorse both methods. Testing may be done with the air supply on. However, this is performance testing, NOT fit testing. Refer to Application Note ITI-029 What You Need to Quantitatively Fit Test Various Brands of Self-Contained Breathing Apparatus Available in the USA on this web site for more information on this subject.

Does TSI offer PortaCount® fit test software for Apple® Computers?

TSI does not currently support software for Apple® computers. There has been some success running the TSI fit test software using Apple software that emulates a PC, however TSI does not have support documentation for this method.

Don't ambient air particles get stuck in the person's lungs?

Only a small percentage of ambient particles become trapped in the test subject's air passages because they are so small. The safety factor of at least 10 that is used for fit testing eliminates any concern.

Has the US Department of Energy (DOE) offered an official opinion on the PortaCount® Respirator Fit Tester?

TSI has an approval letter from the DOE.

How come the Overall Fit Factor calculated by the PortaCount® Respirator Fit Tester isn't the arithmetic average of the individual exercise fit factors?

Averaging fit factors does not produce a valid result. The correct way to compute an overall fit factor is to calculate the average penetration and then convert it to a fit factor. This is what the PortaCount® Respirator Fit Tester does internally and is the method described in OSHA's Respiratory Protection Standard 29CFR1910.134. The number you get is exactly the same as you would have obtained with a chamber system. Refer to the PortaCount Respirator Fit Tester Operation and Service Manual for more detail.

How come the PortaCount® Respirator Fit Tester doesn't use a chamber?

The PortaCount® Respirator Fit Tester does not use a chamber because the challenge aerosol is ever-present in the air we breathe. There is no need to generate and contain the aerosol. These ambient air particles are very small, averaging about 0.05 microns. The PortaCount fit tester is sensitive enough to detect these particles. See Application Note ITI-048 PortaCount Respirator Fit Tester Theory of Operation on this web site or refer to the Operation and Service Manual for more details.

How do you clean masks in between fit tests?

There are several effective ways to clean probed test-respirators in between fit tests. Contact your respirator manufacturer to find out which method they recommend.

How does fit testing with an aerosol challenge agent relate to protection from gaseous hazards?

A mask that fits well enough to stop aerosol leaks will also fit well enough to protect against gases. One reason that the pass level for a fit test is at least 10 times the protection level that is actually expected is to account for differences between gases and aerosols. If you are not familiar with the relationship between "fit factor", "assigned protection factor", and the safety factor of 10 that is used, refer to TSI Applications Note ITI-023 Fit Factors vs. Protection Factors.

How does the PortaCount® Respirator Fit Tester work?

The PortaCount® Respirator Fit Tester works by measuring the concentration of microscopic dust particles in the ambient air and then measuring the concentration of those dust particles that leak into the respirator. The ratio of these two concentrations is called the fit factor. The HEPA filter cartridges stop essentially all the particles so anything that gets into the mask must have come through the face seal. See Application Note ITI-048 PortaCount® Plus Respirator Fit Tester Theory of Operation.

How is the PortaCount® Respirator Fit Tester affected by fluctuations in ambient particle levels?

The PortaCount® Respirator Fit Tester takes an ambient particle measurement before and after each mask sample. The average of the two concentrations is used to calculate the fit factor. This eliminates problems with normal ambient fluctuations. Persons using the PortaCount fit tester should check the ambient particle count using count mode to make sure that there are no wild fluctuations. If fluctuations vary more than 20 percent in 60 seconds, then they should move to a more suitable location.

How long does an alcohol wick last in the PortaCount® Plus Model 8020 Respirator Fit Tester?

The life of an alcohol wick varies depending on the ambient conditions where you do your fit testing. Accumulation of moisture is the most common problem and occurs most often in areas of high humidity. If the Service message comes on and adding alcohol does not cause it to go off, changing the wick is often required. Wicks that have been completely dried out can be reused.

How long does it take to do a fit test with the PortaCount® Respirator Fit Tester?

OSHA requires each of 8 exercises to be at least 60 seconds long except for the grimace exercise which can be as short as 15 seconds. When the PortaCount® Respirator Fit Tester is used with FitPlus™ Fit Test Software for compliance with the new OSHA standard 29CFR1910.134, a fit test will take a total of 7-1/4 minutes.

How many exercises should we be using?

On January 8, 1998 OSHA released a new Respiratory Protection Standard 29CFR1910.134. That standard replaced the fit testing requirements contained in the various substance-specific OSHA standards that have been released by OSHA over the last 20 years. The number of exercises needed for quantitative fit testing is now eight (8). Refer to Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 for information regarding the fit testing requirements of the new OSHA standard. There are other standards besides those from OSHA. Refer to Application Note ITI-046 Standards and Regulations Pertaining to Respirator Fit Testing for details.

How often does OSHA require workers to be fit tested?

The requirement is one fit test, once per year. On January 8, 1998 OSHA released a new Respiratory Protection Standard 29CFR1910.134. That standard replaced the fit testing requirements contained in the various substance-specific OSHA standards that have been released by OSHA over the last 20 years. Refer to Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 for information regarding the fit testing requirements of the new OSHA standard.

How often should the PortaCount® Respirator Fit Tester be re-calibrated or cleaned?

If the only aerosol you use it with is ambient air, your PortaCount® Respirator Fit Tester will not need cleaning more than once a year. The unit should zero using the supplied HEPA filter and pass the maximum fit factor test. TSI recommends annual cleaning and re-calibration. TSI will clean, re-calibrate and, if necessary, replace worn parts for a flat fee.

How often should the Zero Check and Max. Fit Factor Check be performed on the PortaCount® Respirator Fit Tester?

TSI's official recommendation is to always do both checks when you first start fit testing each day. If you want to be more conservative, do both checks each time you turn the PortaCount® Respirator Fit Tester on. Both checks can be completed in less than 2 minutes.

How quickly is the test subject supposed to move his/her head from side to side or up and down when performing the fit test exercises?

OSHA's guidance on this subject is to move the head slowly and hold still for 5 seconds at the extreme of each cycle.

I have an IBM-PC (or compatible) but I don't know if it is equipped with an RS-232 serial port. How can I tell?

Serial ports come in one of two ways on IBM-PC and compatible microcomputers: 25-pin sub-D connectors or 9-pin sub-D connectors. Look on the back of your computer and try to find a 25- or 9-pin D connector with the pins showing (male). D connectors with sockets showing (female) are usually parallel printer ports, not serial ports.

If I obtain my own reagent grade isopropyl alcohol, can I fill the PortaCount® Respirator Fit Tester with it instead of buying TSI alcohol?

Yes. Just make sure the words "Reagent Grade" are on the bottle and no other chemicals are present. Reagent grade isopropyl alcohol is usually 99.5% pure or better. There are other grades that are superior to reagent grade that may also be used. TSI uses isopropyl alcohol from J.T. Baker Chemical Company. We request that you use the same product in order to insure proper operation of the PortaCount® Respirator Fit Tester. J.T. Baker's part number for a 500 ml bottle is 9084-01.

If the PortaCount® Respirator Fit Tester does not count all particles in the air, how can it work?

The PortaCount® Respirator Fit Tester is a ratio measuring instrument. If 10% of the particles are missed during the ambient sample, then 10% are also missed during the mask sample. Since fit factor is a ratio of ambient and mask concentrations, these errors cancel each other out, resulting in the same fit factor regardless of "counting efficiency".

I'm confused about the use of ambient air as the challenge agent. Please explain.

Actually, the PortaCount® Respirator Fit Tester uses the minute dust particles that are always in the air, not the air itself.

No. The PortaCount® Respirator Fit Tester was not designed to be intrinsically safe or explosion proof.

Is there a way to test each person with their own mask rather than with a test mask?

Many of the U.S. respirator manufacturers have begun offering fit test adapters that allow you to fit test using the employee's own respirator. Contact your respirator manufacturer or TSI for more information.

My company has strict requirements regarding the calibration of instruments. How does TSI address this issue?

TSI has a strict, formal calibration procedure that is used and on file. All PortaCount® Respirator Fit Testers are returned from service with As-Found data and a Certificate of Calibration. Customers with specific calibration requirements pertaining to an international calibration standard should contact TSI's Quality Assurance Department at 651-490-2829 or email answers@tsi.com.

My company is having a hard time convincing male employees who wear tight-fitting respirators to shave their beards. Does TSI have any information on the subject?

Yes. Read TSI Applications Note ITI-028 Leakage Measurements on Wearers of Respiratory Protective Equipment with Facial Hair/Beards/Spectacles: Summary of a Literature Search. This is a copy of a magazine article summarizing many recent studies on facial hair. Without exception, every study concludes that facial hair causes poor fits.

My SCBA uses grade-D breathing air. Isn't this particle free?

No. We've measured particle concentrations near 1000 particles per cubic centimeter in grade-D breathing air. The specifications for grade-D air allow for a small amount of particulates measured in milligrams per cubic foot. Ambient particles are so small and light that millions of them add up to almost nothing.

OSHA requires positive-pressure respirators to be fit tested in negative-pressure mode. What do they mean?

Fit testing a positive-pressure respirator in negative-pressure mode is done in one of two ways. One way is to temporarily convert the mask to use HEPA filters instead of the usual air supply. Respirator manufacturers (and TSI) have special fit test adapters available specifically for this purpose. The other way is to share a permanently-probed, negative-pressure version of the same mask. Most respirator manufacturers offer negative-pressure versions of the same face piece used for their SCBAs and PAPRs. OSHA and ANSI endorse both methods.

Should full-face masks be fit tested with the nose cup removed or left in place?

One of the most important things to be concerned with when doing quantitative fit testing is that the mask sample is representative of the air the person is breathing. This usually means sampling from the "breathing zone" near the nose and mouth (a few fit test adapters sample exhaled air instead.) Many full-face masks are probed through the faceplate glass and do not sample breathing zone air when a nose cup is in place. When using such a mask, the nose cup should be removed so there is no barrier between the breathing zone and the sample point. Fit testing with the nose cup in place is OK if the sample is taken from inside the nose cup. Generally speaking, it's best to fit test with the mask configured the same way it is actually used. The bottom line is that as long as the air is being sampled is representative of the air being breathed, do whatever makes you feel comfortable with regard to the nose cup. The nose cup does not contribute to the fit.

The expense of quantitative fit testing instrumentation seems high compared to the cost of qualitative fit testing supplies. How can I justify this expense to my managers?

If you take the time to calculate how much money is spent per year doing qualitative fit testing, including the time employees spend being fit tested, the test operator's time, facilities expenses, benefits and overhead, you will discover that the cost of the QNFT instrumentation is not so significant compared to the enormous improvement in your respiratory protection program. And the instrumentation expense is only one time, not each year. The benefit to your respiratory protection program is that you will be certain that employees have been trained properly. You will be certain that they know how to properly wear a respirator and you will be certain that they have been issued a mask that is the right size. If your company finds itself involved in some litigation, you will have a much stronger case if you can show the results of a quantitative fit test measured by an unbiased instrument, rather than the questionable result of a qualitative test.

The OSHA Respiratory Protection Standard 29CFR1910.134 requires a 15-second grimace exercise. Why is the data from that exercise ignored when the overall fit factor calculation is made?

The purpose of the grimace exercise is to intentionally break the face seal. The fit factor measured during the grimace is irrelevant. What is important is the next exercise. If the respirator reseats itself like it should, the next exercise will get a passing fit factor. If the data from the grimace exercise were to count, people could fail the fit test even though they have a good-fitting respirator. TSI fit testing software allows the data from the grimace exercise to be "excluded" from the overall fit factor calculation. This cannot be done when the PortaCount® Respirator Fit Tester is used without software. The grimace exercise is not part of qualitative fit test protocols because breaking the face seal will always cause the test to fail.

We always use a clean mask for each fit test to avoid spreading germs from person to person, but what about the moisture that collects in the PortaCount® Respirator Fit Tester sample tube. Can someone be exposed to moisture from a previous test subject?

TSI has tested the PortaCount® Respirator Fit Tester and determined that the air flowing through the tubes cannot reverse direction. Refer to Application Note ITI-034 Hygienic Security and the PortaCount fit tester on this web site for details.

We use chemical vapor cartridges in the factory. How does respirator fit using Class 100 (HEPA) cartridges relate to respirator fit with chemical cartridges?

A fit test is a test of the face seal only, not the cartridges. You must fit test with cartridges that prevent passage of the test aerosol (ambient particles) or the test will not work. Since the face seal is not affected by the type of cartridge used, this should not be a concern.

What about the ambient air particles that are trapped in the mask when it is donned?

These particles are purged out as the person breathes. Half masks purge in a few breaths. Full face respirators can take over one minute. If you are following the regulations, you will be insisting that the test subject wear the respirator for at least five or ten minutes before the test begins anyway.

What are the size-fraction definitions for health-related sampling?

The health affects of particles are dependent on where they deposit in the respiratory tract. Particles that can be breathed into the nose or mouth by normal adults are called inhalable. Smaller particles that penetrate into the respiratory tract below the larynx are called thoracic. The smallest particles, the ones that are breathed deep into the alveolar region of the lung, are called respirable.

What do inspirable, inhalable and total particles mean?

The terms "inspirable" and "inhalable" mean the same thing and can be used interchangeably to represent the particles that enter the nose and mouth. The commonly accepted term by the ACGIH/CEN/ISO committees is "inhalable". "Total" particles refer to all particles that are suspended in the air, whether they can be breathed in or not. "Total" usually implies that no inlet conditioning devices have been used to classify the sample.

What do you do if the test subject finishes reading the Rainbow Passage before the exercise is over?

Have him/her start over at the beginning and keep talking until the exercise is complete.

What does NIOSH think of the PortaCount® Respirator Fit Tester?

NIOSH does not certify quantitative fit testing instruments. No one else does either.

What does OSHA think of the PortaCount® Respirator Fit Tester?

On January 8, 1998 OSHA released a new Respiratory Protection Standard 29CFR1910.134. That standard replaced the fit testing requirements contained in the various substance-specific OSHA standards that have been released by OSHA over the last 20 years. The PortaCount® Respirator Fit Tester is specifically listed as an accepted fit test method in Appendix A. Refer to Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 for information regarding the fit testing requirements of the new OSHA standard.

What does the Nuclear Regulatory Commission (NRC) think of the PortaCount® Respirator Fit Tester?

TSI has a letter from the NRC approving the PortaCount® Respirator Fit Tester.

What is a fit factor?

A fit factor is a measure of how well a particular face piece seals against a person's face. It is expressed as a ratio of the concentration of challenge aerosol outside a respirator to the concentration of aerosol that leaks into the respirator through the face seal. A fit factor of 100 means the air inside the mask is 100 times cleaner than the air outside.

What is a suitable substitute for the Rainbow Passage if the test subject cannot read or doesn't speak English?

The reason for the talking exercise is to test the fit of the respirator while the person's mouth and jaw are moving, just like will occur in the work place. It is not really important that the exact language in the Rainbow Passage be used. What is important is that the person speaks loud enough so that others can hear and understand. If the Rainbow Passage cannot be used, have the individual count out loud, or sing, or say almost anything. As long as you simulate talking out loud just like will be done in the work place, you will be achieving the intent of this exercise.

What is respirator fit testing?

Respirator fit testing is a method for determining if a person knows how to wear a particular respirator and if that respirator matches the person's facial features adequately. See Application Note ITI-070 Introduction to Respirator Fit Testing. (Adobe Acrobat reader required)

What is the particle size range in ambient air?

The mean diameter of ambient air particles is typically about 0.08 microns. There are usually almost no particles larger than 0.3 micron.

What is the reason for fit testing respirators?

There are two primary reasons for performing fit tests on respirator wearers—a) Verification of training. After the individual has received respirator training, a fit test is performed to make certain that he/she has truly learned how to properly put on and wear a respirator without assistance. b) Sizing. It is important to make sure that the respirator issued to the individual is capable of providing protection when worn properly-- i.e., it is the right size. Refer to TSI Applications Note ITI-031 Training is the Key to a Good Fit Test Program for some insight on this issue.

What is the typical range of ambient particle concentrations?

Our experience shows that offices range from 3,000 to 30,000 particles per cubic centimeter. Areas that are near industrial processes are much higher.

The 50% cut-off for small particles is 0.02 micrometers (µm). This means that half of the 0.02 µm particles are counted and half are not. As soon as the particle size reaches about 0.04 µm, almost 100% are counted up until a particle size of about 1.0µm. Few particles larger than 1.0 µm are counted by the instrument because they impact and stick inside the switching valve or some other component. Statistically speaking, there are very few particles above 0.1 µm in normal ambient air. The percentage of particles counted is called "counting efficiency". Counting efficiency is also a function of how much alcohol is in the PortaCount® Respirator Fit Tester.

What pass/fail level should my company use?

On January 8, 1998 OSHA released a new Respiratory Protection Standard 29CFR1910.134. That standard replaced the fit testing requirements contained in the various substance-specific OSHA standards that have been released by OSHA over the last 20 years. The minimum pass/fail level for a half mask is 100 and for a full-face mask it's 500. Refer to Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 for information regarding the fit testing requirements of the new OSHA standard. There are other standards besides those from OSHA. Refer to Application Note ITI-046 Standards and Regulations Pertaining to Respirator Fit Testing for details.

What respirator types require fit testing according to OSHA?

OSHA requires that all respirators with tight-fitting facepieces be fit tested. This includes positive pressure masks like PAPR and SCBA. It does not matter how the air gets into the mask. If it is a tight-fitting facepiece, i.e. the performance of the respirator depends on a tight seal between the mask and the user's face, then OSHA requires fit testing. This represents a new requirement mandated in OSHA's Respiratory Protection Standard that was released on January 8, 1998. Refer to Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 for information regarding the fit testing requirements of the new OSHA standard.

When a person fails the fit test, how do I know if the problem is the way the mask is worn, the size of the mask, a bad filter, or a defective mask?

The reason for a poor fit factor can be difficult to determine. The experience of the test operator will often determine how quickly the problem is resolved. Performing a Zero Check and Max. Fit Factor Check as described in the PortaCount® Respirator Fit Tester Operation & Service Manual will tell you if the problem is in the PortaCount fit tester or the mask. If you are using a shared test respirator that has a history of fitting well, you know that the problem is either donning technique or improper size. If you test employees in their own respirator using a fit test adapter, you could also have a defective mask. Trial and error is often the only recourse.

Where do I get probed masks and/or fit test adapters?

Most U.S. respirator manufacturers sell their respirators in "probed" versions for use with quantitative fit testers. Many have begun selling fit test adaptersthat allow you to fit test using the employee's own respirator. Your local respirator supplier should be able to get them easily. Sometimes the supplier may not be aware of this. Get him to inquire directly with the manufacturer. Contact TSI if you have problems obtaining information regarding adapters that are currently available.

Why do other fit test instruments need an aerosol generator and a chamber?

Because the photometers they use are not sensitive enough to detect ambient air particles. They must generate very high concentrations of large particles in order to have a measurable amount of particles leak into the mask.

Studies have shown that during heavy exertion, it is possible to "over breathe" positive-pressure respirators. Since these types of respirators are more likely to be used in extremely hazardous environments, even brief leaks can cause serious injury. In addition, the same two reasons for fit testing negative-pressure masks also apply to positive-pressure masks. 1) Does the individual know how to don the mask properly? 2) What size mask is best for this individual (or in the case of one-size-fits-all masks: Does this mask fit this individual? OSHA did a nice job explaining their reasons for this requirement in the Preamble to the Respiratory Protection Standard. Refer to Application Note ITI-056 Respirator Fit Testing Highlights for OSHA Respiratory Protection Standard 29CFR1910.134 for information on where this information is located within the Preamble.

QNFT is a better test because it eliminates the subjectivity of QLFT. A quantitative fit test is not affected by the person's sense of smell, taste or sensitivity to irritant chemicals. One of the most appreciated aspects of QNFT is that the test subject cannot deceive the test operator, as often happens with QLFT. In addition, QLFT is not technically suitable for determining the high level of fit required for full-face respirators. QLFT's are only designed for a pass/fail level of 100. Since full-face masks require at least 500 or 1000, only QNFT should be used. Refer to TSI Applications Note ITI-032 Don't Use Qualitative Fit Testing for Full-face Respirators for more detail.

Why should a person refrain from smoking for 30 minutes before being fit tested with the PortaCount® Respirator Fit Tester?

We have found that smokers exhale particles for about 30 minutes after smoking. The PortaCount® Respirator Fit Tester sees these particles as particles that leaked into the mask. The result is that the person being tested will not get as high a fit factor as he/she deserves. However, he/she may still pass. The worst thing that can happen is that the person will fail the test. Also, 30 minutes may not be long enough for very heavy smokers.

If the ambient particle concentration is below 1000 particles per cm³ the number of particles that leak into the mask may not be sufficient to make an accurate measurement. An ambient particle concentration that low is rare. Usually it indicates that the PortaCount® Respirator Fit Tester is running low on alcohol.

Will the PortaCount® Respirator Fit Tester work in a hazardous atmosphere?

Our advice is not to try it. Don't use the PortaCount® Respirator Fit Tester in an atmosphere that would require a person to wear a respirator.

ABSOLUTELY NOT! Ordinary isopropyl alcohol is much too dirty to be used in the PortaCount® Respirator Fit Tester. It also contains a lot of dissolved water. The alcohol used in the PortaCount fit tester must be 99.5% to 100% pure isopropyl.